Process for separating nitroglycerin from acid mixtures containing the same.



Patented Oct. 24, 1916.

A. HOUGH. PROCESS FOR SEPARATING NITROGLYCERIN FROM ACID MIXTURES CONTAINING THE SAME.

APPLICATION FlLED OCT. 26. 1914.

sTArns PATENT orrrcn.

ARTHUR I-IOUGH, OF CHOISY, QUEBEC, CANADA.

PROCESS FOR SEPARATING NITROGLYGERIN FROM ACID MIXTURES CONTAINING THE SAME.

Application filed October 26, 1914.

To all whom it may concern:

Be it known that I, An'rnun I'IOUGII, a subject of the King of Great 'Britain, and a resident of Choisy, Province of Quebec, in the Dominion of Canada, have invented a new and Improved Process for Separating Xitroglycerin from Acid Mixtures Containing the Same, of which the following is a specification.

Practically speaking there exist today two processes for separating nitroglycerin from acid mixtures containing the same, one of which may be designated as an economic but dangerous process and the other as a safe but wasteful process. In both of these processes the nitration of glycerin takes place in a nitrator containing nitric and sulfuric acid. the nitric acid heing relied upon to accomplish the nitration of the glycerin and the sulfuric acid to take 'up the water. When nitration is completed. if the operation proceeds according to what I call the dangerous process, its contents are dropped into a separator in which the nitroglycerin rises to the top and is thence withdrawn to a washing tank while the waste acids are withdrawn from the hottom of the separator whence they are introduced into a secondary separator where after standing for many hours a slight amount of nitroglycerin may he still further recovered. The waste or spent acids ohtained from this separator are treated in such a manm as to decompose. any traces of nitroglycerin present. to remove the nitric acid and to concentrate the sulfuric acid which process is common practice in the art of nitroglycerin manufacture. In the separator. along the line at which the force. of specific gravity tends to separate the nitroglycerin from the waste acid there seems to he a constant tendency toward explosion. The nitroglycerin that has separated itself as the result of the force of specific gravity seems to he safe enough after it has once passed through the stage of Separation. hut along the lower line of the nitroglycerin and the upper line of the acid, fiocculcnt matter may often he noticed and local decomposition is unavoidable, occurrences which, unless instantly controlled. result in the explosion of the entire separator. The dangers of this process have resulted in some instances in the use of what may be alled a drowning process in which the contents of the nitrator are allowed to Specification of Letters Patent.

Patented Oct. 24, 1916.

Serial No. 868,596. I

How into a tank containing a large amount of water. It is commonly supposed that nitroglycerin is insoluble in water, and accordingly in this process the nitroglycerin settles at the hottom of the water tank and is withdrawn from there for further treatment. The ditiiculty with -this process is that as a matter of fact. as commonly prac' tised. the recovery of nitroglycerin is out of proportion with the theoretical yield that can he recovered by the soealled dangerous process above described. I have found that the loss due to the drowning process is to be ascrihed to the fact that to a ce'tain extent nitroglycerin is soluble in water and that consequently the water in the drowning tank after the contents of the nitrator are introduced. contains not only water and spent acids. hut also a considerable amount of the nitroglycerin.

It is the ohject of the present invention to devise a process which shall he both safe and economical. avoiding the dangers and wastefulness of the two descrihed processes and the simultaneous recovery of practicall the entire theoretically expected yield.

According to my new process I prefer to startwith a certain definite acid mixture which I prefer to employ for purposes of control. This acid mixture contains about 39']; llXO U1)? I-I SQL. When the nitration is complete. the nitrogylcerin and the spent acids having now a composition approximately of T911 11 50 8% HNO and l t;- ll are introduced into a large drowning tank of cypress wood containing the desired quantity of water. practical and desirahle quantity of water may he in the ratio of t parts water to one part actual acids represented in the charge after nitration. for example a charge of 3.300 pounds of mixed acids and about 583 pounds of glycerin will result in 2,695 pounds of spent acids and 1.400 pounds of nitroglycerin, so that the mostdesirable quantity of water to start with in the drowning tank should be QtWBXtlOTSO pounds I prefer this amount of water for the following reasons: If no cooling coils are used in the drowning tank, an excess of water, such as described, enables the operator to more easily control the temperature during the successive drowningof charges and the changes are not so marked as they would be if a smaller quantity of water were used. Charges from the nitrator are successively introduced into the drowning tank until such time as the desired composition in the tank is reached. The desired composition is such a one that the nitroglycerin from a further charge will no longer be soluble therein. In other words, at this point the liquid is what may be considered a saturated solution of nitroglycerin in a mixture of water, sulfuric acid and nitric acid. From this point on, a certain quantity of the liquid is run oil from the drowning tank; this will be passed on to the acid recovery house. The nitroglycerin is thus precipitated to the bottom of the drowning tank and drawn ofl, to be subsequently treated in the usual manner. The acid composition of the drowning tank (and therefore the amount of nitroglycerin which is soluble in such composition or mixture) is preserved from thls point on by the introduction wlth each succeeding charge from a nitrator of a quantity of water;

When the desired composition in the drowning tank is reached, not only will the nitroglycerin from the nitrator pass through the liquid undissolved, but the nitroglycerin, or a part of it, previously dissolved with the acid and water mixture will be ejected as no longer soluble, so that at this moment it may happen that the recovery of nitroglycerin, which theoretically might be 2.46, may appear to be 3. Once this condition is reached in the drowning tank, the hydrometer reading 'is noted,-I have found it to be about 1.3 S. G.,'and with every fresh charge from the nitrator a fresh supply of water is added to the drowning tank, in this way preserving constantly that proportion of sulfuric acid, nitric acid and water in which the nitroglycerin is insoluble. As the drowning tank is filled by this constant addition of acid, nitroglycerin and water, a part of the liquid is withdrawn to lower the level thereof and from this liquid the acid contents are again recovered. The recovery of these acids since they contain no nitroglycerin is practically free from danger and although there is a very large amount of water to be eliminated, the additional fuel cost is relatively small.

In the drawing furnished herewith there is illustrated a nitrator A connected by means of the discharge pipe 13 with the separating tank (7. The nitroglycerin is withdrawn through the pipe l) at the lower part of the tank connecting the tank C with the tank E. The water supply pipe is indicated as F and the arid \vitlulrawal pipe and tank as (l and ll respectively. The hydrometer is indicated as l.

The essence of the invention will be found in the use of a drowning processin which the drowning liquid is brought to a condition where it will no longer act as a partial .-ol\ out for nitroglycerin, and tliat'condition once brought about should be and can readily be preserved by the addition of a proportionate quantity of water as each new acid charge from the nitrator tends to increase the proportionate quantity of the acids in the drowning tank. The maintenance in the drowning tank of an acid mixture having a substantially constant proportionate constiwater contents of the liquid and the large proportion of sulfuric acid with respect to the water contents. The increases refer to weight.

Having described my invention what I claim is:

1. The process of separating nitroglycerin from acid mixtures in which the nitroglycerin was produced, which consists in introducing the entire body of said acid mixture and said nitroglycerin into a tank containing a large excess of acid mixture and water, the acid and water constituents of said mixture being so proportioned as to constitute a liquid which is saturated with nitroglycerin, and in maintaining said condition by the periodic addition of water with the introduction of each new volume of a body of nitroglycerin and acid.

2. The process of separating nitroglycerin from acid mixtures in which the itroglycerin was produced, which consists in introducing the entire body of said acid mixture and said nitroglycerin into a tank containing a large excess of acid mixture and water, the acid and water constituents of said mixture being so proportioned as to constitute a liquid which is saturated with nitroglycerin, and in maintaining said condition by the periodic addition of water with the in-' troduction of each new volume of a body of nitroglycerin and acid while withdrawing from the tank a. suitable quantity'of its liquid contents to maintain an approximately constant quantity in the tank.

3. The process of separating nitroglycerin from acid mixtures in which the nitroglycerin was produced, which consists in introducing the entire body of said acid mixture and said nitroglycerin into a tank containing a large excess of acid mixture and water, the acid and water constituents of said mixture being composed of sulfuric acid and nitric acid in the approximate pro- 85 quantities of nitric acid with respect to the v lar amount of water and approximately five per cent. of nitric acid, the said mixture being one whichis saturated with nitroglycerin and withdrawing the separated nitroglycerin fromv the bottom of the tank.

5. The process of separating nitroglycerin from the nitric and sulfuric mixtures with which the nitroglycerin was produced,

' which consists in the introduction of the by the introduction of a fresh charge of nitroglycerin and acid.

6. The process of separating nitroglycerin from acid mixtures in which the nitroglyc- Oopies of this patent may be obtained for erin was produced, which consists in introducing the entire body of said acid mixture and said nitroglycerin into a tank containing a large excess of a saturated solution of nitroglycerin in'a mixture of acid and water.

7 The process of separating nitroglycerin from acid mixtures in which the nitroglycerin was produced, which consists in introducing the entire body of said acid mixture and said nitroglycerin intoa tank containing a large excess of a saturated solution of nitroglycerin in a mixture of acid and water and maintaining such condition by periodically adding water with the introduction of each new volume of nitroglycerin and acid. 8. The process of separating nitroglycerin from acid mixtures in which the nitroglycerin was produced, which consists in introducing the entire body of said acid mixture and said nitroglycerin into a tank containing a large excess of a mixture of acid and water, repeatingthis procedure until said mixture of acid and. water has become a saturated solution of nitroglycerin, and then maintaining the saturated condition and the concentration of such solution by the subsequent periodic addition of water with the introduction of each new volume of abody of nitroglycerin and acid.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

v ARTHUR HOUGH.

Witnesses:

FRED A. KLEIN,

JOHN A. FnneUsoN.

five cents cash, by addressing the "Commissioner of Patents. Washington, D. 0. 

